This invention relates generally to methods and apparatus for removing and installing printed circuit boards from/into computer systems and the like and, more particularly, to methods and apparatus of this kind in which the printed circuit boards are extracted and installed laterally from a multi-card chassis without the need to disassemble the system, disturb other cards, or disrupt electrical power from being applied to the chassis.
Personal computers (PCs), PC servers, UNIX servers, and other computer systems typically incorporate chassis that carry a number of printed circuit boards, including input/output (I/O) cards, in connectors arranged in spaced, parallel relationship on a mother board or other support structure. Computer systems of this kind typically incorporate printed circuit boards or cards that are compatible with the standardized Peripheral Component Interconnect (PCI) bus. PCI cards have variable heights and widths, but all have a multiple-contact connector along their lower edges and a bulkhead mounted along an adjacent side edge.
Computer systems of the kind described above typically must be powered down while a faulty PCI card is being removed and replaced. In addition, in many instances, more than just a single card must be removed, because a small-outline card might be located adjacent to one or more full-size cards and thus be inaccessible. This card replacement procedure has proven to be lengthy and disruptive, and it has given rise to the need for a means that allows such cards to be removed and replaced without having to shut down electrical power to the remainder of the system. This is referred to as On-Line Replacement (OLR).
A fully capable OLR system includes OLR hardware, system software and OS support, device drivers, and a user interface. The hardware and software function together to ensure that any OLR activity is benign to other devices connected to the PCI bus. Typically, the PCI OLR hardware isolates the logic and the power signals of a single PCI slot from all other devices connected to the PCI bus. A digital OLR controller arbitrates for the PCI bus and controls all of the logic signals for each slot. Power control electronics allows for power sequencing on the PCI bus, ensuring that power to the card slot is switched off for on-line replacement, while stable power continues to be delivered to other devices on the PCI bus.
OLR solutions have been provided in the past by systems compatible with other industry standards, including VME or Compact-PCI cards, which are of a fixed size, or at most two fixed sizes. In these other systems, the cards are configured to be supported by card guides such that they can be removed and installed without contacting neighboring cards. Typically, the bulkheads of such cards are oriented orthogonal to the direction of extraction, and they incorporate handles and latches, for convenient replacement.
In contrast with the cards of such other industry standards, standard PCI cards are not of a fixed size, but instead have upper and rearward side edges with widely variable positions. In addition, the bulkhead of a PCI card is in line with the normal direction of extraction and is free of handles or other detail for facilitating its extraction. The force required to insert a 64-bit PCI card into a standard connector can be as high as 60 pounds.
Some OLR systems have been devised for use with PCI cards, but they are not considered to be entirely satisfactory. For example, one such system incorporates special adapters and handles, while another incorporates special dividers and guides, along with handles for accommodating size variations and obviating potential electrical shorting of adjacent cards. These known OLR systems for use with PCI cards use standard connectors and maintain a standard extraction procedure, in line with the bulkhead. This generally requires a removal of covers and/or drawers to gain access to the card cage.
It should therefore be appreciated that there is a need for an improved OLR system for use with PCI cards and the like, which facilitates a safe and convenient removal and replacement of the cards in a lateral direction and without requiring a shutdown of electrical power to any other cards. The present invention fulfills this need.